Indium—Tin—Oxide—Silicon heterojunction photovoltaic devices

We have fabricated heterojunction photovoltaic devices consisting of RF-sputtered, highly transparent, and conductive indium-tin-oxide (IT0) films deposited onto both amorphous or crystalline Si. The ITO-amorphous-Si devices exhibit photovoltaic energy-conversion efficiencies of the order of 0.01 percent for the 100-mW/cm2 white light of a tungsten-halogen lamp. However, the relatively high photoresponse of these devices in the blue-UV spectral region leads to a photovoltaic conversion efficiency of approximately 0.5 percent for monochromatic light of wavelength 400 nm. The ITO-crystalline-Si devices exhibit terrestrial solar-cell efficiencies of the order of 1 percent. The performance of such a cell strongly depends on the insulating interface oxide layer, on the surface-state density, and on the incident-light intensity. A model for the operation of these devices is presented and shown to be in quantitative agreement with the experimental data.